Backflow Power Optimization of DAB Based on Asymmetric Duty Cycle and Internal Phase Shift Control

Dual active bridge (DAB) converter with single-phase-shifting (SPS) control would produce large backflow power when voltage regulation ratio deviates from 1 or under light load, an asymmetric duty cycle and internal phase shift (ADIPS) control was proposed which controls the transmission power by duty cycle and internal phase-shift ratio and the backflow power can be eliminated under light load, thereby improving the efficiency of DAB converter. By establishing mathematical models of inductor current and transmission power, the working principle of the proposed control method was given as well as the cause of backflow power was analyzed. The constraints of zero backflow power and an optimization control method of zero backflow power under ADIPS control are presented. Finally, an experimental prototype is used to obtain the validation results, simulation and experimental results verify the excellent performance of the proposed control strategy in eliminating the backflow power of the DAB converter under light load.